PROJECT SUMMARY/ABSTRACT Early detection of cancer provides one of the most effective ways to reduce cancer related morbidity and mortality. Unfortunately, early detection of cancers is hindered by several factors, including the lack of suitable tests and cost. Personalized medicine and technological advances are changing the approach to cancer diagnosis. Blood based liquid biopsy has provided an opportunity for the development of early detection tests. However, most malignancies do not have effective minimally invasive strategies for early detection and certain pre-neoplastic or neoplastic conditions are not readily detectable using blood based assays. One of the chief challenges in developing minimally-invasive tests is the identification of the appropriate biofluid and cancer specific biomarkers. Over the past two decades, DNA released from cancer cells has emerged as a specific clinical biomarker of cancer. We have previously developed sensitive methods for detection of this released tumor DNA (rtDNA) and demonstrated its potential applications in variety of clinical samples. We have extensive preliminary results that biofluids associated with certain cancers are significantly enriched in rtDNA when compared to blood. Our group has developed sensitive methods to detect and quantify rtDNA in numerous biofluids. In addition, our group has an ongoing relationship with an industrial partner, PapGene Inc that has already participated in the clinical development of liquid biopsy applications. This project will build on those strengths to develop tests for the detection of brain, head and neck, and colon cancers in cerebrospinal fluid, saliva, and stool, respectively. A non-plasma based liquid biopsy approach for the earlier detection of cancers or premalignant lesions difficult to detect in the blood would represent a significant medical advance.